This invention relates to thermal protection circuits and structures for electronic devices and cables.
Portable electronic devices such as portable computers, handheld media players, and cellular telephones typically contain connectors that receive power signals from other electronic devices such as desktop computers and power adapters. The power signals are typically conveyed over cables such as Universal Serial Bus (USB) cables. A user who desires to use a portable electronic device or who desires to charge a battery in the portable electronic device may connect the device to a source of electricity such as a power adapter using a cable.
Conventional cables and connectors for cables and electronic devices can fail in the presence of moisture. In particular, when the cables or connectors become wet, conductive dendritic structures form in the dielectric material being used to isolate conductive structures that are at different potentials in the cables or conductors. Once a conductive dendritic structure forms in the dielectric material between the conductors, the two conductors are effectively shorted together. This short circuit condition can lead to excessive current and an undesirable buildup of heat. In some situations, the heat that is produced may melt part of the cable or connector and cause a failure.
It would therefore be desirable to be able to provide thermal protection circuits and structures for electronic devices and cables.